Breeding

DNA-based genetic profiling gives vets, breeders and pet owners an easy means of verifying parentage, managing disease and determining the likelihood that puppies will display other important traits.

By Cyndi Tebbel

Every nucleated human cell, and those of animals, plants and bacteria, contains the molecule known as deoxyribonucleic acid or DNA. The molecular structure DNA was discovered in 1953 by James Watson and Francis Crick, who revealed that DNA held the genetic information or ‘blueprints’ that determine an organism’s unique characteristics. It was such an astounding scientific breakthrough that it earned them the 1961 Nobel Prize in physiology.

Since the mid-1980s DNA profiling or fingerprinting has become a common means of confirming paternity, detecting the genetic mutations that cause disease and solving crimes.

“You can take hair follicles, a bit of saliva, blood off another animal, fence paling or clothing,” says George Sofronidis, Manager of the Molecular Division at Melbourne’s ASAPLaboratories. “Then the breed identification test can identify the breed and the dog.”

ASAP is currently working with Mars Veterinary on developing a Wisdom PanelTM Insights breed identification test for Australia. Already available in the US, Canadian and UK markets, the test identifies over 190 breeds, the diseases that can affect those breeds and information on the possible size of the dog. Having information on your dog’s ancestry means you can tailor what Mars calls a ‘wellness program’ to fit its individual needs.

Popular tests

Aside from determining parentage, breed-specific DNA-based genetic testing is also used to identify the carriers of around 50 hereditary diseases, as well as what Sofronidis refers to as the ‘nice to know’ traits, such as coat colour.

DNA samples can be taken from animals of all ages, typically via a cheek swab or blood test, with results available in a number of days or weeks, depending on the test. One of the most commonly requested tests is clear-by-parentage, which is testing the dam and sire for genetic diseases to ensure that all of their puppies will be free from those conditions.

“Once you verify both parents' genetic health status as being clear of that disease then the puppy is obviously free of those diseases and so its referred to as clear-by-parentage,” Sofronidis explains. “However, the puppy should still be tested and its parentage confirmed. There is also the ability to screen for carriers, and puttingtwo carriers together may produce an affected pup.”

DNA testing is generally carried out by breeders or veterinarians. Genetic information can be collected by individuals, but Sofronidis cautions that such testing requires positive verification via a microchip number or approved tattoo scheme. He recommends independent collection through a vet or collection agent to ensure results will be accredited.

Who’s doing it?

Since DNA testing was introduced to the veterinary and pedigree market around eight years ago, the uptake from breeders has been positive, with around 20-30 per cent now using it. Sofronidis expects those numbers to increase now that testing has become more affordable, and because of increased awareness and the breeding programs developed by breed clubs. “Breed clubs promote the tests on their websites and they don’t want non-tested dogs to be used in breeding programs,” Sofronidis says.

Pet owners are also availing themselves of this service, according to Dr Amanda Chin from Animal Network. “As inherited disease awareness increases we’ve seen an increase in the number of tests requested by pet owners who have recently purchased a pedigree dog as a pet,” Dr Chin says. “We encourage breeders and pet owners to always ask for a history of inherited disease in a pedigree line before purchasing a dog.”

Why test?

There are several good reasons to test any breeding stock for genetic disease, but in the end, each of them boils down to improving the health of the breed.

With the launch of the Department of Primary Industries Code of Practice for the Responsible Breeding of Animals with Heritable Defects that cause Disease in 2009, Victorian breeders are now bound by the Act to ensure their breeding programs are set up for the long-term health and wellbeing of their pedigree line.

In other states, says Dr Chin, most breeders who choose to register with their state authority are motivated by a desire to do the right thing for the breed. “But puppy farms that breed dogs for the purpose of making money often do not show the required level of care and welfare for the breed,” she explains.

Evidence shows that testing is reducing the level of hereditary disease. Sofronidis says the perfect example is the Labrador Retriever Club, which has been testing for hips and elbows for 10 years. “They’ve got a very popular dog, so they have to be proactive,” he says.

Testing is important for the welfare of animals, of course, but Dr Chin points out that as it improves the perception of the genetic health of Australian pedigree dogs, it also makes them more valuable and desired overseas.

ANKC requirements

Dr Peter Higgins, a veterinary surgeon and member of the ANKC Canine Health Committee, says the ANKC recommends DNA testing for all stud dogs so that breeders know all they can about their dogs’ health and the health of future litters.

DNA testing for studs was introduced by the ANKC in 2004, and the ANKC National Code of Practice for Hereditary Diseases requires that all members work to reduce the incidence of hereditary disease in their breeds.

Because breeders own the information collected via DNA testing, it’s up to them to make it available to the public. Sofronidis hopes that most breeders list clear, carrier and affected dogs on an open register, such as the Veterinary Genetic Assurance (VGA) Certification Program.

ASAP Labs and Animal Network both share the data they collect for the benefit of vets, individual breeders, breed clubs, the public, animal associations such as Customs and Guide Dogs Australia, and welfare groups including the RSPCA.

Don’t pass it on

DNA is used to screen dogs for the following:

• Simple DNA profiling to verify identity, parentage and pedigree

• Traits such as coat colour, long hair or the natural bob tail

• Disease

When testing for disease, generally there are three possible results:

• Clear or normal: the disease-causing gene is not present, so the dog cannot pass on a disease gene to its progeny.• Carrier: of the pair of chromosomes responsible for whether or not the dog is affected, one is disease-causing and one is not. The dog is a ‘carrier’ – it will not exhibit disease symptoms or have medical problems as a result, but will pass on the disease gene to 50 per cent of its offspring, on average.• Affected: both of the genes are the disease-causing variant and the dog will be medically affected by the disease, as well as passing on a disease-causing gene to its offspring.

More information

The ANKCCanine Health Committee works to improve breeders’ awareness of and ability to reduce hereditary disease. Visit the ANKC website for more information about committee initiatives.W: www.ankc.org.au

Dr Amanda Chin is Business Manager of the Animal Products Division at Animal Network, the animal DNA testing business of Genetic Technologies.T: 1800 822 999E: